The present invention relates to the art of transferring electronic data. It finds particular application in conjunction with the transfer of image data among electronic medical diagnostic equipment such as CT scanners, magnetic resonance imagers, digital x-ray, and other equipment that generates, processes or displays digital image information. However, it is to be appreciated that the invention will also find application in other areas, particularly areas which transfer large blocks of data.
Heretofore, medical diagnostic information has commonly been processed at each individual CT scanner, digital x-ray device, magnetic resonance imager or the like. Most often, the digital information is recorded on a removable disk or tape to facilitate carrying the image to other remote viewing locations. At the remote viewing locations, the radiologist could operate on the image data with various image enhancement algorithms and routines to enhance the diagnostic value for a particular application while the CT or other scanner was used to conduct further patient examinations. Rather than storing the image information on individual, portable disks. Some hospitals have installed a central computer system with a large memory capacity for storing all digital images and other diagnostic data.
Difficulty has arisen in transferring the image data among the scanners, the central archiving computer, distributed viewing terminals, and other stations. An image is typically about 4 megabytes of data. With improvements in the scanners and in the processing speed of the generated data, images will be made up of progressively larger blocks of digital data. Blocks of data of this magnitude are most easily transmitted on dedicated, direct transmission or communication lines. That is, with communication lines which interconnect each viewing terminal, for example, with each potential source of images. However, such direct dedicated lines are expensive and switching among them is inefficient. Moreover, conflict management, such as the conflict between several viewing terminals all requesting images from the same archive computer or CT scanner at the same time, are difficult to resolve.
More commonly, data is transferred among a plurality of stations or nodes on a common data bus. Various schemes have been developed for sharing the common bus, such as frequency or time division multiplexing. Most commonly, an asynchronous time division protocol is utilized.
To prevent packets of transmitted data from colliding or interacting on the data bus, various polling policies have been established. Commonly, a distributed polling policy is implemented, although central polling is also well known. Typical distributed or self polling schemes include token ring, logic ring, and the like.
On the whole, the hardware and protocols associated with central bus and ring architecture have high associated overhead. This overhead reduces the efficiency of the system and increases data transfer times. Moreover, these distributed systems and protocols were designed for applications with relatively small data packets by the standards of image data transfers. The prior art systems were also designed for flexibility to handle a wide range of applications. This flexibility again increases the overhead with no productive advantage in image data transfer applications.
Typically, at each data bus node, data is collected in the buffers of a file server from one or more sources. This data is recopied into a transport protocol hardware which adds its appropriate headers or other information. The data is copied from the buffers of the transport protocol to buffers of a queuing and multiplexing level, which again adds headers and other information to the data. The queuing and multiplexing level also oversees placing the data on the bus media in an efficient and fair way by the data link hardware. At the receive end, the data is again recopied from buffer to buffer as it is moved through the same layers, doubling the overhead.
The present invention provides a new and improved data transfer network which overcomes the above referenced problems and others.